The present invention pertains to oscillator apparatus for use in transponders, repeaters and the like wherein a single pulse of radio frequency waves may be transmitted to the transponder, repeater, etc. for the activation thereof. Once activated the transponder, repeater, etc. retransmits one or more pulses at the same frequency. It is essential in this system that the oscillator apparatus remember the received radio frequency and retransmit at the same frequency.
In prior art devices, the received frequency at the transponder, repeater, etc. is remembered in a digital memory circuit or the like. Because of the complex storage device used in prior art systems, these prior art systems are large, complex and costly. Further, the length of time required for the oscillator to lock on to the incoming signal is generally relatively slow so that the pulse of radio frequency waves must be relatively long.